Variable resistance controls are well known in the prior art. Such controls are utilized in a multitude of electronic devices to control the flow of electrical current. More particularly, variable resistance controls are used in appliances, in stereo and video equipment, and in automobiles. In an automobile, for example, a variable resistance control is utilized to vary the intensity of the lights in the instrument panel. Such variable resistance controls are often commonly referred to as "dimmer switches."
Generally, variable resistance controls comprise an electrical conductive path or collector strip and an electrical resistance path carried on a base. A movable contactor or contact means is provided which bridges the resistance path and the conductive path. The control device also includes some type of a knob which allows a user to rotate or move the contactor relative to the resistance path and the conductor path so as to vary the output resistance of the device. The variable resistance control device may include conductive and resistance paths that are linear or circular (arcuate) in design. Also, the resistance path may be continuous or it may be formed by a series of discreet resistor pads. In a variable resistance control device that employs discreet resistors, as each successive conductive pad is contacted by a movable contactor, an additional single resistor is added in series to the power supply and the load. An example of a prior art variable resistance control having a circular configuration and a continuous resistance path may be found in U.S. Pat. No. 4,371,862. An example of a prior art variable resistance control having a linear configuration and resistance path formed by a series of discrete resistors may be found at page 49 of the article entitled "Porcelainized-Steel Substrates Gain Favor For PC Boards, Hybrids" by John Tsantes which appears in the Jun. 22, 1980 issue of the Electronic Design News.
Variable resistance control devices are utilized both with and without lubricants. In some applications, such as that discussed in U.S. Pat. No. 4,931,764, a variable resistance control is utilized without any type of a lubricant on the resistance or conductive paths of the device. More particularly, the device of the '764 patent is used as part of a sensor in gasoline, thus it is not possible nor desirable to utilize a lubricant. In other applications, it is desirable to utilize a non-conductive lubricant on the conductive path of the variable resistance control device. The lubricant is added to the surface to reduce friction during the wiping of the contactor on the resistance path. In addition to helping to extend the life of the variable resistance control, the lubricant may also provide a more pleasing "feel" as a user adjusts the contactor. Unfortunately, the use of a lubricant in prior art variable resistance controls has created a problem in some applications. More particularly, in some applications the lubricant has interfered with the electrical connection between the conductive path and the contactor. This problem can create interruptions in the otherwise desirable continuous flow of current. Applicant believes that these interruptions are primarily caused by the hydroplaning effect of the lubricant on the contactor.
The present invention provides an improved lubricated variable resistance control that does not suffer from the current interruptions experienced with some prior art lubricated variable resistance controls.